The study represents an analysis of pulmonary platelet aggregation, fibrinogen deposition, plasminogen and serotonin release as a consequence of soft tissue trauma, hemorrhagic shock and/or superimposed embolization. The techniques of Cr51 tagged platelets and I125 tagged fibrinogen, coupled with the techniques of fibrin plate assessment of tissue plasminogen activity and immunoassay of pulmonary venous effluent will be applied to provide these results. Models will be studied in the dog, rat and pig, with the latter being used to provide a determination of platelet aggregation. Neural and hormonal inputs to this process will be assessed utilizing the denervated lung in which denervation is effected by autotransplantation and also by studying the effects of cerebral hypoxemia. In addition, the hormonal influence will be assessed by determining the effects of adrenalectomy, adrenalectomy plus steroid supplement and steroid therapy itself on the process of intrapulmonary platelet aggregation and coagulation. Finally, the hormonal aspects will be evaluated in the rat using the hypophysectomy preparation. The therapeutic effects of Dextrans, aspirin, methysergide and methylprednisilone will be evaluated by defining which of the parameters, i.e., platelet sequestration, fibrinogen deposition, plasminogen activation and serotonin release are altered by these therapeutic modalities.